Editing Lichen (section)

===Substrates and habitats===
[[File:Der Heilige Dominikus am Nordturm des Regensburger Doms.jpg|thumb|upright|Lichens on a limestone statue on a tower of [[Regensburg Cathedral]]]]
Lichens grow on and in a wide range of substrates and habitats, including some of the most extreme conditions on earth.<ref>{{Cite news|url=https://www.nytimes.com/2019/11/19/science/lichens-plants-evolution.html|title=In the Race to Live on Land, Lichens Didn't Beat Plants|first=JoAnna|last=Klein|newspaper=The New York Times |date=19 November 2019}}</ref> They are abundant growing on bark, leaves, and hanging from [[epiphyte]] branches in [[rain forest]]s and in [[temperate woodland]]. They grow on bare rock, walls, gravestones, roofs, and exposed soil surfaces. They can survive in some of the most extreme environments on Earth: [[arctic tundra]], hot dry [[desert]]s, rocky coasts, and toxic [[slag heap]]s. They can live inside solid rock, growing between the grains, and in the soil as part of a [[biological soil crust]] in arid habitats such as deserts. Some lichens do not grow on anything, living out their lives blowing about the environment.<ref name=WIL/>

When growing on mineral surfaces, some lichens slowly decompose their substrate by chemically degrading and physically disrupting the minerals, contributing to the process of [[weathering]] by which rocks are gradually turned into soil. While this contribution to weathering is usually benign, it can cause problems for artificial stone structures. For example, there is an ongoing lichen growth problem on [[Mount Rushmore National Memorial]] that requires the employment of mountain-climbing conservators to clean the monument.<ref name="WaPo11Jul2005">{{cite news |title=For Mount Rushmore, An Overdue Face Wash |url=https://www.washingtonpost.com/wp-dyn/content/article/2005/07/10/AR2005071000754.html |access-date=20 August 2022 |newspaper=[[The Washington Post]] |agency=Associated Press |date=11 July 2005}}</ref>

Lichens are not [[parasites]] on the plants they grow on, but only use them as a substrate. The fungi of some lichen species may "take over" the algae of other lichen species.<ref name=LLHE/><ref name=ABGPPU>{{cite web |url=https://www.anbg.gov.au/cryptogams/underworld/panel-6/index.html |title=Pollution, The Plant Underworld |publisher=Australian National Botanic Gardens |access-date=10 October 2014 |archive-url=https://web.archive.org/web/20140217122343/https://www.anbg.gov.au/cryptogams/underworld/panel-6/index.html |archive-date=17 February 2014 |url-status=dead }}</ref> Lichens make their own food from their photosynthetic parts and by absorbing minerals from the environment.<ref name=LLHE/> Lichens growing on leaves may have the appearance of being parasites on the leaves, but they are not. Some lichens in ''Diploschistes'' parasitise other lichens. ''Diploschistes muscorum'' starts its development in the tissue of a host ''Cladonia'' species.<ref name=Honegger1988/>{{rp|30}}<ref name=Dobson/>{{rp|171}}
[[File:Lichen A 01.jpg | thumb | 220x124px | right | Lichen on a fallen branch]]

In the arctic tundra, lichens, together with [[mosses]] and [[liverworts]], make up the majority of the [[ground cover]], which helps insulate the ground and may provide forage for grazing animals. An example is "[[reindeer moss]]", which is a lichen, not a moss.<ref name=LLHE/>

There are only two species of known permanently submerged lichens; ''[[Hydrothyria venosa]]'' is found in fresh water environments, and ''[[Verrucaria serpuloides]]'' is found in marine environments.<ref>{{cite journal |last1=Ahmadjian |first1=V. |title=Lichens are more important than you think |journal=BioScience |date=1 March 1995 |volume=45 |issue=3 |page=1 |doi=10.1093/bioscience/45.3.124 |url=https://academic.oup.com/bioscience/article-abstract/45/3/124/252273?redirectedFrom=PDF |access-date=14 September 2021}}</ref>

A crustose lichen that grows on rock is called a ''[[saxicolous lichen]]''.<ref name=ASLGPZ/><ref name=VMBMLF>''Mosses Lichens & Ferns of Northwest North America'', Dale H. Vitt, Janet E. Marsh, Robin B. Bovey, Lone Pine Publishing Company, {{ISBN|0-295-96666-1}}</ref>{{rp|159}} Crustose lichens that grow on the rock are [[epilithic]], and those that grow immersed inside rock, growing between the crystals with only their fruiting bodies exposed to the air, are called ''[[endolithic lichen]]s''.<ref name=LNAILV/><ref name=VMBMLF/>{{rp|159}}<ref name=ASLGAF/> A crustose lichen that grows on bark is called a ''[[corticolous lichen]]''.<ref name=VMBMLF/>{{rp|159}} A lichen that grows on wood from which the bark has been stripped is called a ''[[lignicolous lichen]]''.<ref name=ASLGGO>{{cite web|url=http://www.lichens.lastdragon.org/faq/glossary2.html|title=Alan Silverside's Lichen Glossary (g-o), Alan Silverside|access-date=10 October 2014|archive-url=https://web.archive.org/web/20141102105836/http://www.lichens.lastdragon.org/faq/glossary2.html|archive-date=2 November 2014|url-status=live}}</ref> Lichens that grow immersed inside plant tissues are called ''[[endophloidic lichen]]s'' or ''[[endophloidal lichen]]s''.<ref name="LNAILV" /><ref name=VMBMLF/>{{rp|159}} Lichens that use leaves as substrates, whether the leaf is still on the tree or on the ground, are called ''[[Epiphyllous lichen|epiphyllous]]'' or ''[[foliicolous lichen|foliicolous]]''.<ref name=UNOLP/> A ''[[terricolous lichen]]'' grows on the soil as a substrate. Many squamulose lichens are terricolous.<ref name=VMBMLF/>{{rp|159}} ''[[Umbilicate lichen]]s'' are foliose lichens that are attached to the substrate at only one point.<ref name="LNAILV" /> A ''[[vagrant lichen]]'' is not attached to a substrate at all, and lives its life being blown around by the wind.